Australia has announced a $20m increase in disaster assistance to the Philippines, as further delays hamper aid distribution to increasingly desperate survivors.

The government will also deploy further defence force (ADF) support, including an additional RAAF C-130J Hercules to assist the two aircraft already there. A C-17A Globemaster will be on standby. The battleship HMAS Tobruk has also been diverted to the Philippines, with the ADF citing its accommodation, amphibious lift, and aircraft-carrying capabilities.

The $20m will be divided between various NGOs, with the bulk of it ($9m) to the United Nations’ appeal. Up to $2m will also be spent on the deployment of an medical team ($1m) and specialists from the AFP and Dfat.

Unicef's regional adviser, Chris de Bono, spoke to Guardian Australia from the Philippines late on Wednesday evening, and said aid had finally begun to flow but was still being delayed by distribution centres that were not yet set up.

“There are some problems and things aren’t getting there as fast as they should,” he said.

“I think the Filipino army and government tried really hard to open up the routes in but it took a long time purely because of the difficulties involved.”

As government and military eventually cleared roads into Tacloban, hordes of people took the chance to get out, blocking access in for aid deliveries and assistance.

De Bono said while it was “perfectly understandable” the chaos “turned into a spiral”.

“The capacity at the moment to get in what’s needed just doesn’t exist. This capacity is increasing by the hour but so to is the frustration.”

On Tuesday, eight people died when a crowd looking for food rushed a warehouse. Authorities said 10,000 bags of rice were carried away by crowds but the eight people were crushed when a wall collapsed.

“I do know that there are tensions in Tacloban,” said De Bono. “It’s no surprise to anyone that there are very frustrated people. They don’t have enough to eat and they don’t have enough to feed their children.

“People not having access to sanitation, water and food and shelter will cause death. Children are the most vulnerable members of the community and they suffer the most.”